Alexander Graf of SuSE has updated his EFI patch for U-Boot, adding the ability to boot from El Torito-style ISOs:

efi_loader: Support loading from El Torito isos

Some distributions still provide .iso files for installation media. To give us greatest flexibility, this patch set adds support for El Torito booting with EFI payloads.

  iso: Make little endian and 64bit safe
  iso: Start with partition 1
  iso: Allow 512 byte sector size
  efi_loader: Split drive add into function
  efi_loader: Add el torito support
  efi_loader: Pass file path to payload
  efi_loader: Increase path string to 32 characters
  distro: Enable iso partition code

For more information, see the full patch:
http://lists.denx.de/mailman/listinfo/u-boot